With current synchronisation problem between instances, choosing a big instance is a no brainer. I don't want to use small instance and got 404 when searching community on other instance or when not all comments from other instances showed up.

I use Gboard because the prediction is better than the others. As a Japanese speaker, the choice is limited.

Asteroid problem is more solvable than political problem.
Armageddon solved it like in 2 hours or so.

Yeah, in the end to move you need your interest (or topic or interesting person you want to follow) to exist in Mastodon. For most people, the topic (or interesting people they want to follow) only exist in Twitter, so there's no incentive for them to move from Twitter.

not enough of those famous and important people moved from Twitter to Mastodon

This is the reason I'm still using Twitter. I use Twitter not to tweet about what I did, but to get news from people I follow.
Tech people can move to Mastodon because their circles are moving, but not with common people.
For me, personally, Mastodon is like empty void. No one to follow and I can't interact with people who share same interests because they only exist on Twitter (since the "famous people" isn't moving from Twitter)

If their phone stuck in Android 11 in 2023, I doubt there will be any updates from OnePlus.